In an air conditioner for a vehicle and an air conditioner duct, it has been required to reduce noise caused by a flow of air, particularly, generated at locations adjacent to air suction openings and air discharge openings from being transmitted into a passenger compartment of the vehicle. In an air conditioner disclosed in Japanese Patent publication No. 2004-243816, for example, a noise absorbing member is attached to an inner surface of an air conditioning case housing a blower unit and defining an air passage so as to reduce the noise.
In this case, however, since the noise absorbing member is additionally attached to the air conditioning case, an area of passage reduces. To maintain the area of passage, the thickness and the size of the noise absorbing member are necessarily reduced. Therefore, it is difficult to sufficiently reduce the noise. Otherwise, it is necessary to increase the size of the air conditioning case.
Also, it is known to form an air conditioner duct with a noise absorbing material as disclosed in Japanese Patent publication No. 2001-322544, for example. In the air conditioner duct, a film is arranged along an outer surface or an inner surface of a noise absorbing layer made of a glass wool. The film restricts air from passing through the duct from an inside to an outside, but permits vibrations of air from the inside to outside of the duct, thereby to reduce the noise caused by air passing therethrough.
In this case, the noise absorbing layer needs to have the sufficient hardness so that the air conditioner duct can stand alone. However, the lower the hardness of a noise absorbing member is, the higher the noise absorbing effect is. Therefore, it may be difficult to have the noise absorbing effect sufficiently in the above duct. Also, in a case that the film is arranged on the outer surface of the duct, the film is likely to be easily broken when the duct is handled.